What is one thing Benjamin Franklin is famous for?

Why this is the answer

Five answers are accepted: U.S. diplomat, oldest member of the Constitutional Convention, first Postmaster General of the United States, writer of "Poor Richard's Almanac," and started the first free libraries. You need only one, and "diplomat" is the shortest. USCIS counts Franklin among the most influential of the Founding Fathers, and he earned all five over a long and busy life as a printer, author, politician, diplomat and inventor. He trained as a printer and was an accomplished one by his mid-twenties, then began writing books and papers. Poor Richard's Almanac became his most famous publication. He organized America's first library, whose members lent books to one another. He was active in colonial politics, and in 1775 the Second Continental Congress made him the first postmaster general. The Constitution would later list the power to establish post offices among the powers of Congress. His diplomacy may have mattered most. A diplomat travels to other countries to represent the United States, and Franklin went to England and France many times in that role. The fighting stopped after the British Army surrendered at Yorktown, Virginia, in 1781, and Franklin helped negotiate the 1783 treaty in which Great Britain agreed that the United States had won the war and was an independent nation. He also sat in the Constitutional Convention as its oldest delegate and signed the Constitution. In the interview, use the list's words rather than a description of the man. Franklin was an inventor, so "he invented things" is a natural reply, but inventor is not one of the five answers on the 2008 list and may not be accepted. The same goes for "he was a Founding Father": true, and still not on the list. Choose one item and say it cleanly. "First Postmaster General" or "oldest member of the Convention" leaves no room for doubt.